Continuation of work funded under Ey 01128-02, on spatial, temporal and chromatic interactions. Using both Maxwellian-view and CRT display techniques, we are studying visual responses to steady, moving and flickering gratings. Chromatic responses are measured with constant-luminance gratings, and luminous responses with constant-chromaticity gratings. Combining various flicker rates and spatial periodicities, we will explore the spatio-temporal frequency domain with and without image stabilization. The SRI Purkinje Eyetracker will be used both to stabilize the retinal image and to study the effects of various stimuli on the eye-movements being measured. Comparing striped gratings to other patterns such as checkerboards and circular targets, we have found threshold changes that can be predicted only in terms of the two-dimensional Fourier transforms of these patterns. Correct predictions cannot be obtained from the local contrasts of the stimulus (or from one-dimensional Fourier analysis). Since these Fourier properties affect both luminous and chromatic responses equally, they may arise before the luminous-chromatic specialization of pathways; i.e., in the retina. If so, they should be strongly affected by image stabilization. BIBLIOGRAPHIC REEFERENCES: D.H. Kelly. Luminous and chromatic flickering patterns have opposite effects. Science 188, 371-372 (1975).